Implantable medical devices (IMDs) may be provided for monitoring a physiological condition or signal and/or delivering a therapy to a patient. Examples of IMDs include pacemakers, cardioverter defibrillators, cardiac monitors which may monitor hemodynamic function and/or cardiac electrical signals, neurological stimulators, insulin monitors, oxygen monitors, pressure monitors, drug delivery pumps and more. Generally, IMDs may be equipped with a fixation device or mechanism that anchors the IMD at a desired implant site. The fixation device or mechanism may provide passive fixation that stabilizes the IMD position by passively pressing against or interacting with the body tissue or anatomical structures at the implant site without piercing the patient's tissue. In other examples, the fixation device or mechanism may provide active fixation that anchors the IMD in position by piercing or penetrating the patient's body tissue at the implant site. Stable positioning of the IMD at a desired implant site is generally important in ensuring beneficial and reliable function of the IMD.
In some clinical applications, an IMD may be tested or physiological signals may be acquired at multiple anatomical sites before an optimal implant site for the IMD is selected, based on the testing or acquired physiological signals. The fixation device may make repositioning of the IMD from one test site to another test site difficult or challenging. At least in the case of active fixation devices, moving an IMD between multiple sites for testing may cause undesired tissue injury at the multiple sites.